Allow h1-h6 & hgroup in <legend>
Allow h1-h6 & hgroup in <legend>

Fixes https://github.com/validator/validator/issues/418 Thanks @stevefaulkner

validator/validator,tripu/validator,validator/validator,validator/validator,takenspc/validator,takenspc/validator,takenspc/validator,tripu/validator,tripu/validator,validator/validator,takenspc/validator,tripu/validator,validator/validator,takenspc/validator,tripu/validator